1. Field of the Invention
The invention generally relates to a light filter element and a projection apparatus, and more particularly, to a color wheel module and a projection apparatus adopting the color wheel module.
2. Description of Related Art
Digital light processing (DLP) projection apparatus is configured to filter an illumination beam emitted by a light source into three lights in red color, green color and blue color (R, G and B) through a high-speed rotary color wheel, and then the three lights are transmitted to a light valve to be converted into an imaging beam. The imaging beam is projected through a projection lens onto a screen to form frames. By continuously altering the angle of a micro mirror on the light valve in association with the high-speed rotary color wheel and taking advantage of the effect of the persistence of vision, a pixel can give out different color variations.
In general, a color wheel includes different dichroic filters and a rotating part (for example, a motor's rotor). In addition, in order to cause the on/off state of each micro mirror on the light valve matched to the rotation of the color wheel, an index mark is disposed on the rotating part of a color wheel module and the position of the index mark is sensed by a light sensor to obtain the position of the color wheel or a filter region of the color wheel through which the illumination beam passes so as to project out an image with desired color.
If the color wheel and the light sensor are in an open environment, however, it is likely caused that dust is very easily deposited on the color wheel and the light sensor so as to decrease the brightness of the illumination beam too fast and affect the normal operation of the projection apparatus. In addition, if temperature of the color wheel is too high, it may cause the motor to be overheated or the adhesive between the components of the color wheel to be melted, which causes the projection apparatus fail to be normally operated as well.
U.S. Pat. No. 6,755,554 discloses a color wheel unit, wherein a color wheel is fixed at a body of the color wheel unit and covered by a cover of the color wheel unit. China Utility Patent No. 201562114U discloses a projector comprising a light source device, a color wheel and a first heat-dissipating model.